Salmonella enterica

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Salmonella enterica
Salmonella enterica serovar typhimurium 01.jpg
S. enterica Typhimurium colonies on a Hektoen enteric agar plate
Scientific classification
Kingdom: Eubacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Salmonella
Species: S. enterica
Binomial name
Salmonella enterica
(ex Kauffmann & Edwards 1952)
Le Minor & Popoff 1987
Subspecies

S. enterica subsp. arizonae
S. enterica subsp. diarizonae
S. enterica subsp. enterica
S. enterica subsp. houtenae
S. enterica subsp. indica
S. enterica subsp. salamae

Salmonella enterica (formerly Salmonella choleraesuis) is a rod-shaped, flagellated, facultative anaerobic, Gram-negative bacterium and a member of the genus Salmonella.[1]

Epidemiology[edit]

Main article: Salmonellosis

Most cases of salmonellosis are caused by food infected with S. enterica, which often infects cattle and poultry, though also other animals such as domestic cats[citation needed] and hamsters[2] have also been shown to be sources of infection to humans. However, investigations of vacuum cleaner bags have shown that households can act as a reservoir of the bacterium; this is more likely if the household has contact with an infection source, for example members working with cattle or in a veterinary clinic.

Raw chicken eggs and goose eggs can harbor S. enterica, initially in the egg whites, although most eggs are not infected. As the egg ages at room temperature, the yolk membrane begins to break down and S. enterica can spread into the yolk. Refrigeration and freezing do not kill all the bacteria, but substantially slow or halt their growth. Pasteurizing and food irradiation are used to kill Salmonella for commercially produced foodstuffs containing raw eggs such as ice cream. Foods prepared in the home from raw eggs such as mayonnaise, cakes, and cookies can spread salmonella if not properly cooked before consumption.

Pathogenesis[edit]

Secreted proteins are of major importance for the pathogenesis of infectious diseases caused by Salmonella enterica. A remarkable large number of fimbrial and non-fimbrial adhesins are present in Salmonella, and mediate biofilm formation and contact to host cells. Secreted proteins are also involved in host cell invasion and intracellular proliferation, two hallmarks of Salmonella pathogenesis.[3]

Nomenclature[edit]

Salmonella enterica has 6 subspecies, and each subspecies has associated serovars that differ by antigenic specificity.[4] There are over 2500 serovars for S. enterica.[5] Salmonella bongori used to be considered a subspecies of S. enterica, but it is now the other species in the Salmonella genus. Most of the human pathogenic Salmonella serovars belong to the S. enterica subsp. enterica subspecies. These serogroups include Salmonella Typhi, Salmonella Enteritidis, Salmonella Paratyphi, Salmonella Typhimurium, and Salmonella Choleraesuis. The serovars can be designated as written in the previous sentence (capitalized and non-italicized following the genus), or as follows: "S. enterica subsp. enterica, serovar Typhi."

See also[edit]

References[edit]

  1. ^ Giannella RA (1996). Salmonella. In: Baron's Medical Microbiology (Barron S et al., eds.) (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1. (via NCBI Bookshelf). 
  2. ^ Swanson SJ, Snider C, Braden CR, et al. (2007). "Multidrug-resistant Salmonella enterica serotype Typhimurium associated with pet rodents". New England Journal of Medicine 356 (1): 21–28. doi:10.1056/NEJMoa060465. PMID 17202452. 
  3. ^ Hensel M (2009). "Secreted Proteins and Virulence in Salmonella enterica". Bacterial Secreted Proteins: Secretory Mechanisms and Role in Pathogenesis. Caister Academic Press. ISBN 978-1-904455-42-4. 
  4. ^ http://www.textbookofbacteriology.net/salmonella.html
  5. ^ Medical Microbiology (6th ed.). Philadelphia, PA: Mosby Elsevier. 2009. p. 307. 

External links[edit]